The invention concerns a process to manufacture a back-adhering material for an inner book of a hard cover book whereby a sheet of cotton fabric is pretreated by being washed, desized, bleached and dried, and then laminated with a paper sheet with an adhesive, and the resulting laminate is calendered to smooth and harden it.
The created laminate is glued to the inner book on the spine from narrow rolls parallel to the inner book. The gauze acts like a hinge for the inner book. In efficient book manufacturing, the laminate is applied to the inner book spine before the inner book is rounded, and the laminate is stretched while rounding the inner book spine. The laminate must permit this stretching without tearing. The laminate is sufficiently elastic in the direction of the weft thread, i.e., perpendicular to the lengthwise direction of the sheet, but not in the direction of the warp thread. The laminate can only be used in narrow rolls whose width corresponds to the width of the inner book plus 2xc3x9710 mm of side overlap.
In hardcover production using perfect binders, wide rolls are used where the width of the wide roll consists of the untrimmed inner book height plus at least 2xc3x975 mm overlap for both sides. Prior art hinge material from wide rolls is not sufficiently elastic in a lengthwise direction because the warp thread of the fabric is not sufficiently elastic. At present, wide-roll machines (perfect binders) can only use a crepe paper that consists of a base paper of 70-90 g that is sufficiently elastic in the lengthwise direction to allow the inner book spine to be rounded. The stability of the inner book spine consisting only of crepe paper is limited after the inner book has been rounded and hardened. This is particularly problematic for thicker books.
To compensate at least slightly for the poor quality of hardcovers made with perfect binders, a somewhat involved process is pursued. After the crepe paper is applied to the inner block and trimmed, and the inner book spine is rounded in the book processing line, an additional work station is included in the process in which gauze is applied to the crepe paper. Apart from the additional machine expense, the gauze is shorter than the length of the trimmed inner book. The gauze hence does not provide a 100% bond between the inner book spine and the book cover. Tears can arise at the overlaps at the top and bottom of the spine. Of course, the gauze strips applied after rounding the inner book do not require and do not have any elasticity perpendicular to their length.
The problem of the invention is hence to create a process that allows a hardcover book to be produced on wide-roll machines (perfect binders) with more stable back-adhering material, especially elastic, laminated gauze.
This problem is solved by a process according to patent claim 1.
Thanks to the fact that the still-moist laminated sheet of material gathers or shrinks in a lengthwise direction before it dries, the sheet of material is given a flat, fine creping that is elastic in the warp direction. This elasticity can be set between 5% to approx. 15% and is sufficient for wide-roll machines to round thick inner books. The gauze coated with paper on one is a suitable starting material for the sheet of laminated material as is used successfully on narrow roll machines. The hinge material that is subsequently provided with the flat fine creping can hence be used for hardcover production on wide roll machines instead of the crepe paper that has been used by itself to date. This substantially increases the stability of the inner book spine.
Different processes can be used to crepe the material. It is easiest to crepe the laminate material with a doctor blade after the material is moistened. The doctor blade compresses the material somewhat. Then the sheet that is compressed in a lengthwise direction is dried and the creping becomes fixed. However, the creping from this procedure would then be too coarse with the danger of the fabric separating from the paper. Another type of creping can be attained in a machine with different roller speeds. Usually, however, the creping is not fine enough even with this procedure, and cross-wise waves arise in the sheet of material which makes the sheet limp and difficult to process in perfect binders.
In an development of the invention, the fine creping of the laminate is created by sanforizing in which the moist laminate material sheet is guided between a stretched, thick rubber belt and a drying cylinder and crimped. The drying cylinder dries the paper and the fabric and simultaneously fixes the residual shrinkage of the laminate. The attained fine creping produces a residual shrinkage of ca 10-15% in the final product.
In a final step, the laminate is preferably dried on a felt calender. This preferably consists of a steam-heated roller with a surface temperature of 100-160xc2x0 C. around which runs a felt cloth. The laminated sheet is guided between the felt cloth and the steam-heated roller and dried. The laminate is then wound with as little tension as possible.
The laminate back-adhering material does not require any technical changes different from crepe paper in the book-binding machines that are used for further processing. The new laminate has improved running properties, and the jams that frequently arise in crepe paper are eliminated or at least reduced since the material from the wide roll is guided to the inner book via a suction feeder. Unavoidable fluctuations in crepe paper height cause the crepe to jam in the suction feeder when no air flows through the crepe. The hinge material according to the invention is contrastingly more even and flatter so that the process of bringing the laminate to the inner book by the blown air is improved. There are also no problems when cutting the laminate according to the invention in the perfect binder. A book binder who uses exclusively perfect binding can create the same high-quality hardcover books with an inner book thickness over 4 cm on wide roller machines with the laminate manufactured according to the invention. The laminate is applied to the inner book before trimming and rounding the inner book spine, and the material is stretched in the rounding station. The elasticity can be greater than is possible with narrow roll machines.